A third wave is coming, promises Walsh's spokesman, who now stresses his boss's efforts to protect not just children, as originally stated, but also students -- including ones who are already adults.

Earlier this year, Walsh announced that his office would seize property and assets of any dispensary within 1,000 feet of a school that had been ordered to cease operations or relocate and chose not to do so. Here's how he described his rationale in a late February statement, released after the closure of 22 dispensaries -- the first recipients of letters from the U.S. Attorney:

"Thanks to the excellent work of the DEA, working hand in glove with prosecutors from the U.S. Attorney's Office, we were able to close marijuana stores that sold a Scheduled I Controlled Substance within 1,000 feet of a school. These stores were closed without incident. This effort is about protecting children from illegal drugs, and maintaining drug free zones around our schools in compliance with federal law."

Golden Alternative Care, near the Colorado School of Mines, received a shutdown letter.

"Universities are considered schools," he says. "That is part of the definition of the Drug Free School Zone Act," which provides for escalating drug-offense punishment within 1,000 feet of a school.

But rather than using the term "children," as Walsh did in his previous statement, Dorschner substitutes "students," as in this comment: "The U.S. Attorney's goal from the beginning was to essentially enforce the enhanced penalties regarding the distribution and manufacture of marijuana in or near schools or colleges -- and the purpose of that is to protect students from marijuana stores."

Page down to continue reading about the closure of 25 dispensaries and future actions.

Boulder's Med Shed also received a closure letter.

The 25 retail outlets that received letters in March pulled the plug without incident. While five so-called enforcement actions were necessary the first time around, none were required on Monday.

In a news release about this development, Coloradans with information about a dispensary that may be within 1,000 feet of a school are encouraged to contact the U.S. Attorney's Office via e-mail at usaco.jwalsh@usdoj.gov. According to Dorschner, this same exhortation was shared a month or so back, and folks have responded.

"After we announced the initiative, we have periodically received calls and e-mails from members of the public asking that the DEA look at certain stores and their proximity to certain schools," he says. "They run the gamut from people calling and wondering whether a certain marijuana store is within 1,000 feet of a neighborhood school all the way to individuals who conduct their own investigations and submit to investigators maps with names of dispensaries, names of schools and their estimated calculation of distance. And some of these charts have been quite sophisticated."

Dorschner doesn't know if any of these contacts have prompted an investigation that led to a closure letter, but it's certainly a possibility, particularly given the pending third wave of missives. "I can't commit to a certain time frame" for their distribution, he says. "but I know we continue to work on identifying schools and confirming their proximity to the stores."

Will the third wave be the last? In Dorschner's words, "It's too early to tell."